A top Ohio supporter of Governor Mitt Romney will switch sides and endorse Rick Santorum in Columbus this afternoon, a campaign source said.

The source declined to make public the identity of the switching surrogate.

While Ohio Gov. John Kasich remains neutral, Romney has the support of a handful of top current and former Ohio officials, including Attorney General Mike DeWine, Rep. Jim Renacci, and former Senator George Voinovich.

A spokeswoman for DeWine, Lisa Peterson Hackley, said “I can neither confirm nor deny” that he is the switcher, and declined to say what the State Attorney General will be doing at 2:00 p.m.

Update 12:05 p.m.: Santorum mentioned DeWine a few minutes ago at a campaign event in Shelby Township, Michigan while talking about how 2006 was a bad election year for Republican candidates.

“Everybody lost in 2006,” Santorum said. “You know, Mike DeWine in Ohio lost by 15 points in the state of Ohio. And by the way he became the Attorney General of Ohio, he came back four years later and won.”